1. Field of the Invention
The present invention relates to an extension to the use of an electro-anaesthesia apparatus preferably employed in the domain of dental care.
2. Description of the Related Art
This electronic device is based on the use of D.C. currents and it has formed the subject matter of an earlier Patent Application by the Applicant, published under No. 2 659 241. The disclosure of FR 2 659 241 is incorporated herewith in its entirely. Schematically, it comprises a control housing and electrodes interchangeable depending on the mode of use chosen by the practitioner. This electronic device is shown in FIG. 1, in which the same reference numerals are used as in the FR 2, 659 241 application, for ease of reference.
One of the electrodes is constituted by the tool used during the operation (instruments, turbines), while the second electrode is none other than a member for gripping the housing, held by the patient. The two are consequently in simultaneous contact with two parts of the patient's body when the practitioner is carrying out his operation, and the electric circuit is closed for the duration of work of the tool in the mouth.
The source of direct current makes it possible to obtain currents adjustable in the microamp and milliamp ranges, whose uses are adapted to the various applications of the device. This latter comprises means for adjusting the intensity, for switching the polarities and/or scale, a means for visually monitoring the intensity of one or more electric signals, as well as electrically switchable outputs.
One of the major advantages of this apparatus is that it is easy to adapt it to the patient's threshold of sensitivity. In fact, if there is a domain where inequality particularly exists, it is in the sensation of pain felt by man. Certain people are virtually insensitive to stimuli considered to be painful by others, while others react to the least stimuli. This is particularly true concerning teeth. The fact that one is close to the nervous centres, which "manage" pain, is probably not irrelevant.
In the present case, the anaesthesic threshold may be rapidly adapted by modifying the intensity of the current, and even the current scale, depending on the case. The device lends itself well to this ease of adjustment, in view of its simplicity resulting from the fact that it is question only of a simple source of current, whose intensity may be modified by a knob located on the housing.
Up to the present time, practitioners employed this electro-anaesthesia device with their traditional tools of the odontological instruments, turbines, etc. . . type. The tool is then in contact with the dentine and the current is transmitted to the dentine via the metal electrode constituted by said tool, via the drill. It is therefore the tool itself which induces the anaesthesic effect.
This type of dental electro-anaesthesia proves satisfactory in nearly 90% of cases, and is explained by a hyperpolarization of the nervous fibers by the polarized current which blocks the nervous influx, vector of pain.
From the practitioner's point of view, in addition to the considerable versatility of use already mentioned, mention may also be made of the immediate anaesthesic effect reduced to the duration of the operation alone, the immediate and permanent control of the sensitivity, the total absence of toxicity, the absence of risk of allergy, etc. . . To this must be added the less purely scientific dimension of the patient's participation, who reacts to the stimuli felt. The therapy/patient binomial thus reconstituted, each participates in the operation as actor.
However, these advantages do not conceal the fact that the domain of application theoretically covered by this apparatus was up to the present time confined to certain applications which clearly follow from the generic name of the treatment: dentine electro-anaesthsia, as its name indicates, concerns only anaesthesic applications of operations on the dentine.
In other words, operations as painful as scaling of the teeth or paradontic curetting did not seem to be concerned by the advantages of the apparatus mentioned.
Several reasons were opposed to the increasing demand of practitioners attracted by the ease of use and the efficiency of the device and who would, of course, have wished to extend them to the field of scaling. In the first place, it appeared obvious that a device based on an electrical phenomenon of conduction of current would be inefficient for an operation concerning the enamel of the teeth, which, as is known, constitutes an excellent insulator. Here, the limitation follows from the characteristics of conductivity of the parts of the body treated.
In the second place, the very nature of the treatment, obtained by vibrations of a tip placed in contact with the enamel, seemed to be an obstacle. In fact, the vibrations may for example be produced thanks to a system of piezoelectric type supplied by an electric energy source leading to the production of ultrasonic mechanical vibrations with the aid of the piezoelectric crystal. In order to insulate the technical device, based on an electromechanical phenomenon, it was heretofore usual to envelop it in a plastified sheath constituting the handle of the tool. Consequently, there were no possible interferences between the internal electric phenomenon and the user.
In brief, a tool with plastic handle is traditionally used for scaling a tooth, while the apparatus forming the subject matter of the discussion, being an electrode, is necessarily metallic. The obstacle is that the tool is in that case the seat of two theoretically independent electrical phenomena, one electromechanical with the use of piezo-electricity, and the other purely electrical with the passage of the current in the tool, of which it is not known whether they interfere on one another, and even with the user.
These various reasons explain that, up to the present time, the invention forming the subject matter of patent application No. 2 659 241 had never been used for a scaling operation.